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LEE S. CHADWICK, OF EAST CLEVELAND, AND MARC RESEK, CLEVELAND HEIGHTS,

OHIO, ASSIGNORS TO THE CLEVELAND METAL PRODUCTS COMPANY, OF CLEVELAND,

OHIO, ACOBAPORATION OF OHIO.

TREATMENT or IRON on. s EEL Ton. THE PREVENTION or OXIDATION on. aUs'TINm No Drawing.

vented acertain new and useful Improve ment in the Treatment of Iron or Steel for the Prevention of Oxidation or Busting, of

which the following is a full, clear, and exact description.

This invention relates to improvements in the art of treating iron or steel articles, or articles having a coating of iron or steel, for the purpose of preventing the oxidation or rusting thereof, and wherein such articles are provided with a protective covering adapted to render the surfaces thereof capable of resisting, or of being unaffected by the action of, moisture and other oxidizing influences.

It has heretofore been proposed to treat iron or steel (or articles composed of or having a surface of iron or steel) With a dilute solution of ordinary phosphoric acid (Ll-1,1 0 and preferably in the presence of iron filings or other compound intended to control or regulate the rapidity or strength of the chemical action upon the metal or a-rticles undergoing treatment. It has been found that, in the practice of such process, it is necessary to boil the articles for a considerable length of time. Furthermore, the coating which is obtained upon the surfaces of the iron or steel articles is composed only of a mixture of normal ferric and ferrous phosphate.

We have ticles in a bath containing a solution of the di-hydrogen phosphate of any metal (except the alkali metals) or by boiling such articles in a bath or solution containing chemicals in the proper proportion to form such a di-hydro'gen phosphate, We are able to form upon the iron or steel surface a coat ing consisting essentially of a compound or mixture of normal phosphateof iron and a phosphate of the metal in solution, which coating is not only superior inits resisting qualities to any other so-called rust-pro coating with which we are acquainted but which coating can be formed upon the article in a much shorter time than is required for the production of any other coat- I Specification of Letters Patent.

found that, by boiling such ar- Patented Nov. 4, 1919.

Application flled February 6, 1917. Serial No. 146,989.

ing, for the purpose specified, with which We are acquainted. The metals employed for the production of such di-hydrogen phosphates are less basic than iron, Which results in dissolvin a certain amount of the ron and depositing upon the undissolve'd iron not only the compound or mixture of norm-a1 phosphate of iron and a phosphate of the metal in solution, but also a certain amount of the metallic constituent of the phosphate.

The bath employed by us may contain any normal phosphate of a metal less basic than 1ron or any mono-hydrogen phosphate, together with a suflicient quantity of an acid tq furnish the necessary hydrogen to form a di-hydrogen phosphate and a sufficient qu-antlty of any metallic compound to form the soluble di-hydrofgen phosphate of that metal (exceptalkaline compounds, compounds of antimony, and mercuric chlorid). As nearly all metals form such soluble dihydrogen phosphates, this necessarily includes compounds of nearly all metals ex cept those mentioned.

One of the distinguishing features of our process is that in the practice of the same,

no free phosphoric acid is present in the bath to which the iron or steel articles are SubJected. In preparing such a 'bath, the following ingredients may be used:

Ordinary sodium phosphate, which is crystallized, di-sodium, mono-hydrogen phosphate;

Blue vitriol, or copper sulfate crystals;

Sulfuric acid.

.VVhen these ingredients are mingled, the

reaction which takes place is believed to be as follows gallons of boiling water a quantity of this solution that will contain about 1 T lbs. of blue vitriol and a proportionate amount of each of the other ingredients. After treatphosphate or any other alkali phosphate copper sulfate we may use manganese dicases a volatile acid will be given off by volatilized.

phosphate of the metal of the'metallic salt proofing in accordance with our process deposited upon and embedded therewith,

ing the articles for a period of, say 40 minutes', it will be found that, under ordinary conditions they are completely and satisfactorily coated. When it is desired to treat a new, batch of articles, the bath in the tank may be brought up to standard strength by adding thereto about one-sixteenth of the amount of,the standard solution originally introduced. c

In place of sodium phosphate, ammonium the rust-resisting qualities of such surface as well as impart thereto the capability of receiving speclal additional treatment, such plating with copper or other metals.

e in the formula hereinbefore set forth may be increased so as to furnish an excess of such metallic salt sufficient to secure the coating of metal (copper) upon the compound phosphate ofiron and such metal (copper). Where a coating of metallic copmay be employed. Furthermore, in place of ing will be manifest to the eye because of the reddish appearance thereof; and the amount of such coating may be varied by suitably varying the excess of the copper sulfate over the amount set forth in the aforesaid formula, and this -variation in the coating will be manifested by a like variation in the redness thereof.

' Having thus described our invention, what We claim is 1. The process of treating iron or steel, or articles composed of or having a surface of iron or steel, which includes subjecting the said article to the action of a bath made from a solution of an alkali-phosphate and a salt of'a metal less basic than iron, to-

oXid, zinc sulfate, aluminum chlorid, copper carbonate, or any other compound of a metal other than an alkali compound or compounds of a few metals, like barium, which do not form soluble phosphates. Furthermore, while any rather strong acid (such as acetic, hydrochloric, or sulfuric) can be used, a nonvolatile acid, such as sulfuric, gives the best results, as insome boiling the solution, requiring the addition of a relatively large quantity of fresh acid to take the place of that which has been thus When the articles have been boiled in the bath "consisting of the dilute solution described hereinbefore, the coating produced thereupon consists of a compound or mixture of normal phosphate of iron and the gether with an acid.

2. The process of treating iron or steel, or articles composed or having a surface of iron or steel, which includes subjecting the same to the action of a bath made from 'an aqueous solution of an alkali phosphate and a compound ofa metal which Will form a soluble phosphate, together with sulfuric acid.

3. The process of treating iron or steel, or articles composed or having a surface of iron or steel, which includes subjecting the in solution. In some cases this mating is formed together with a coating of the metal of such salt.

It has been found in practice that mixtures of the following phosphates, metal salts, and acids work successfully in rustphosphates Metal salts Acids same to the action of a bath containing the sodium phosphate. Copper sulfate. Acetic acid. dlhyfirogen p fif a metal less b94546 I; g; j: g igg ig i than iron and not containing free phosphorlc 3 CoPPQrc'arbonate. Sul f ricac id: acid or any x g g Alummum chlorid. Manganese dioxid. Zinc oxid. Silver nitrate.' Iron sulfate. Copper chlorid.

By employing a slight excess of the metallic salt over thatvrequired to form a di-' hydrogen phosphate of metal, the coating formed upon the articles treated will, as indicated above, contain, in addition to the compound phosphate of iron and the metal constituent of the salt, a coating of such metal constituent, additional to such phosphates, and which will be combined and and a compound 0 a metal less basic than embedded. with such phosphate coating. 'iron which will form a soluble phosphate. Where copper sulfate is employed as the J 6. The process of treating iron" or steel, or metallic salt, the phosphate coating upon articles composed of or having a surface of the iron or steelmay have metallic copper iron or steel, which includes subjecting the same to the action of a bath containing a solution of the di-hydrogen phosphate of a metal less basic than iron.

7. The process of treating iron or steel, or

4. The process of treating iron or steel, ,or articles composed of or having a surface of iron or steel, which includes subjecting the same to the action of a bath containing a solution of the di-hydrogen ortho-phosphate of a metal less basic than iron and not conu I Ammonium phosphate.

taining an oxidizing agent.

5 The process of treating iron or steel, or artlcles com osed of or having a surface of ,same to a bath made from a solution of an alkali phosphate to ether with sulfuric acid and this metallic copper willnot -only-adhere firmly to the surface on which it is de-. posited, but will, byits presence, enhance proportion of copper sulfate appearing iron or stee which includes subjecting the per is obtained, .the presence of such coat- I articles composed of or having a surface of iron or steel, which includes subjecting the same to the action of a bath containing a solution of the di-hydrogen phosphate of a metal less basic than iron together with a small amount of another salt of such metal and which is capable of dissolving iron and depositing its metal constituent.

8. The process of treating iron or steel, or articles composed of or having a surface of iron or steel, Which includes subjecting the same to the action of a bath containing a solution of copper di-hydrogen phosphate together with a small amount of copper sulfate.

9. In the treatment of iron or steel, or articles composed of or having a surface of iron or steel, subjecting such iron or steel to the action of copper di-hydrogen phosphate and copper sulfate.

10. A soluble compound for treating iron or steel, or articles composed of or having a surface of iron or steel, said compound containing an alkali phosphate, an acid, and a compound of a metal less basic than iron Which will form a soluble phosphate.

11. Iron or steel, or articles composed of or having a surface of iron or steel, furnished With a coating containing iron phosphate combined With metallic copper.

/ phosphate combined With a metal. less basic than iron.

In testimony .Whereof, We hereunto afiix our signatures in the presence of two Witnesses.

LEE S. CHADWICK. MARC RESEK.- Witnesses:

W. E. SHEPPARD, K. G. EAST; 

